Abstract

We mapped the NGC 1333 section of the Perseus Molecular Cloud in the J = 2-1 emission lines of {sup 12}CO and {sup 13}CO over a 50' × 60' region (3.4 × 4.1 pc at the cloud distance of 235 pc), using the Arizona Radio Observatory Heinrich Hertz Submillimeter Telescope. The angular resolution is 38'' (0.04 pc) and velocity resolution is 0.3 km s{sup –1}. We compare our velocity moment maps with known positions of young stellar objects (YSOs) and (sub)millimeter dust continuum emission. The CO emission is brightest at the center of the cluster of YSOs, but is detected over the full extent of the mapped region at ≥10 × rms. The morphology of the CO channel maps shows a kinematically complex structure, with many elongated features extending from the YSO cluster outward by ∼1 pc. One notable feature appears as a narrow serpentine structure that curves and doubles back, with a total length of ∼3 pc. The {sup 13}CO velocity channel maps show evidence for many low-density cavities surrounded by partial shell-like structures, consistent with previous studies. Maps of the velocity moments show localized effects of bipolar outflows from embedded YSOs, as well as a large-scale velocity gradientmore » around the central core of YSOs, suggestive of large-scale turbulent cloud motions determining the location of current star formation. The CO/{sup 13}CO intensity ratios show the distribution of the CO opacity, which exhibits a complex kinematic structure. Identified YSOs are located mainly at the positions of greatest CO opacity. The maps are available for download as FITS files.« less

@article{osti_22340167,
title = {THE ARIZONA RADIO OBSERVATORY CO MAPPING SURVEY OF GALACTIC MOLECULAR CLOUDS. IV. THE NGC 1333 CLOUD IN PERSEUS IN CO J = 2-1 AND {sup 13}CO J = 2-1},
author = {Bieging, John H. and Revelle, Melissa and Peters, William L.},
abstractNote = {We mapped the NGC 1333 section of the Perseus Molecular Cloud in the J = 2-1 emission lines of {sup 12}CO and {sup 13}CO over a 50' × 60' region (3.4 × 4.1 pc at the cloud distance of 235 pc), using the Arizona Radio Observatory Heinrich Hertz Submillimeter Telescope. The angular resolution is 38'' (0.04 pc) and velocity resolution is 0.3 km s{sup –1}. We compare our velocity moment maps with known positions of young stellar objects (YSOs) and (sub)millimeter dust continuum emission. The CO emission is brightest at the center of the cluster of YSOs, but is detected over the full extent of the mapped region at ≥10 × rms. The morphology of the CO channel maps shows a kinematically complex structure, with many elongated features extending from the YSO cluster outward by ∼1 pc. One notable feature appears as a narrow serpentine structure that curves and doubles back, with a total length of ∼3 pc. The {sup 13}CO velocity channel maps show evidence for many low-density cavities surrounded by partial shell-like structures, consistent with previous studies. Maps of the velocity moments show localized effects of bipolar outflows from embedded YSOs, as well as a large-scale velocity gradient around the central core of YSOs, suggestive of large-scale turbulent cloud motions determining the location of current star formation. The CO/{sup 13}CO intensity ratios show the distribution of the CO opacity, which exhibits a complex kinematic structure. Identified YSOs are located mainly at the positions of greatest CO opacity. The maps are available for download as FITS files.},
doi = {10.1088/0067-0049/214/1/7},
journal = {Astrophysical Journal, Supplement Series},
number = 1,
volume = 214,
place = {United States},
year = {Mon Sep 01 00:00:00 EDT 2014},
month = {Mon Sep 01 00:00:00 EDT 2014}
}

We present the results of a program to map the Sh2-235 molecular cloud complex in the CO and {sup 13}CO J = 2 − 1 transitions using the Heinrich Hertz Submillimeter Telescope. The map resolution is 38″ (FWHM), with an rms noise of 0.12 K brightness temperature, for a velocity resolution of 0.34 km s{sup −1}. With the same telescope, we also mapped the CO J = 3 − 2 line at a frequency of 345 GHz, using a 64 beam focal plane array of heterodyne mixers, achieving a typical rms noise of 0.5 K brightness temperature with a velocity resolution of 0.23 km s{sup −1}.more » The three spectral line data cubes are available for download. Much of the cloud appears to be slightly sub-thermally excited in the J = 3 level, except for in the vicinity of the warmest and highest column density areas, which are currently forming stars. Using the CO and {sup 13}CO J = 2 − 1 lines, we employ an LTE model to derive the gas column density over the entire mapped region. Examining a 125 pc{sup 2} region centered on the most active star formation in the vicinity of Sh2-235, we find that the young stellar object surface density scales as approximately the 1.6-power of the gas column density. The area distribution function of the gas is a steeply declining exponential function of gas column density. Comparison of the morphology of ionized and molecular gas suggests that the cloud is being substantially disrupted by expansion of the H ii regions, which may be triggering current star formation.« less

We present fully sampled 38'' resolution maps of the CO and {sup 13}CO J = 2-1 lines in the molecular clouds toward the H II region complex W3. The maps cover a 2.{sup 0}0 x 1.{sup 0}67 section of the galactic plane and span -70 to -20 km s{sup -1} (LSR) in velocity with a resolution of {approx}1.3 km s{sup -1}. The velocity range of the images includes all the gas in the Perseus spiral arm. We also present maps of CO J = 3-2 emission for a 0.{sup 0}5 x 0.{sup 0}33 area containing the H II regions W3more » Main and W3(OH). The J = 3-2 maps have velocity resolution of 0.87 km s{sup -1} and 24'' angular resolution. Color figures display the peak line brightness temperature, the velocity-integrated intensity, and velocity channel maps for all three lines, and also the (CO/{sup 13}CO) J = 2-1 line intensity ratios as a function of velocity. The line intensity image cubes are made available in standard FITS format as electronically readable files. We compare our molecular line maps with the 1.1 mm continuum image from the BOLOCAM Galactic Plane Survey (BGPS). From our {sup 13}CO image cube, we derive kinematic information for the 65 BGPS sources in the mapped field, in the form of Gaussian component fits.« less

We present 38'' resolution maps of the CO and {sup 13}CO J = 2-1 lines in the molecular clouds toward the H II region complex W51. The maps cover a 1.{sup 0}25 x 1{sup 0} section of the galactic plane and span +30 to +85 km s{sup -1} (LSR) in velocity. The spectral resolution is {approx}1.3 km s{sup -1}. The velocity range of the images includes all the gas in the Sagittarius spiral arm. Color figures display the peak line brightness temperature, the velocity-integrated intensity, and 2 km s{sup -1} channel-averaged maps for both isotopologs, and also the CO/{sup 13}COmore » J = 2-1 line intensity ratio as a function of velocity. The CO and {sup 13}CO line intensity image cubes are made available in standard FITS format as electronically readable tables. We compare our molecular line maps with the 1.1 mm continuum image from the BOLOCAM Galactic Plane Survey. From our {sup 13}CO image cube, we derive kinematic information for the 99 BGPS sources in the mapped field in the form of Gaussian component fits. The integrated {sup 13}CO line intensity and the 1.1 mm source flux density show only a modest degree of correlation for the 99 sources, likely due to a range of dust and gas physical conditions within the sources. However, the 1.1 mm continuum surface brightness and the integrated {sup 13}CO line intensity for small regions containing single BGPS sources and molecular clouds show very good correlations in many cases. Differences in the shapes of these correlations from one spatial region to another probably result from different physical conditions or structure in the clouds.« less

We have made new CO observations of two molecular clouds, which we call 'jet' and 'arc' clouds, toward the stellar cluster Westerlund 2 and the TeV γ-ray source HESS J1023–575. The jet cloud shows a linear structure from the position of Westerlund 2 on the east. In addition, we have found a new counter jet cloud on the west. The arc cloud shows a crescent shape in the west of HESS J1023–575. A sign of star formation is found at the edge of the jet cloud and gives a constraint on the age of the jet cloud to be ∼Myr.more » An analysis with the multi CO transitions gives temperature as high as 20 K in a few places of the jet cloud, suggesting that some additional heating may be operating locally. The new TeV γ-ray images by H.E.S.S. correspond to the jet and arc clouds spatially better than the giant molecular clouds associated with Westerlund 2. We suggest that the jet and arc clouds are not physically linked with Westerlund 2 but are located at a greater distance around 7.5 kpc. A microquasar with long-term activity may be able to offer a possible engine to form the jet and arc clouds and to produce the TeV γ-rays, although none of the known microquasars have a Myr age or steady TeV γ-rays. Alternatively, an anisotropic supernova explosion which occurred ∼Myr ago may be able to form the jet and arc clouds, whereas the TeV γ-ray emission requires a microquasar formed after the explosion.« less

In order to precisely determine the temperature and density of molecular gas in the Large Magellanic Cloud, we made observations of the optically thin {sup 13}CO(J = 3-2) transition using the ASTE 10 m telescope toward nine peaks where {sup 12}CO(J = 3-2) clumps were previously detected with the same telescope. The molecular clumps include those in giant molecular cloud (GMC) Types I (with no signs of massive star formation), II (with H II regions only), and III (with H II regions and young star clusters). We detected {sup 13}CO(J = 3-2) emission toward all the peaks and found thatmore » their intensities are 3-12 times lower than those of {sup 12}CO(J = 3-2). We determined the intensity ratios of {sup 12}CO(J = 3-2) to {sup 13}CO(J = 3-2), R {sup 12/13}{sub 3-2}, and {sup 13}CO(J = 3-2) to {sup 13}CO(J = 1-0), R {sup 13}{sub 3-2/1-0}, at 45'' resolution. These ratios were used in radiative transfer calculations in order to estimate the temperature and density of the clumps. The clumps have a kinetic temperature range of T{sub kin} = 15-200 K and a molecular hydrogen gas density range of n(H{sub 2}) = 8 x 10{sup 2}-7 x 10{sup 3} cm{sup -3}. We confirmed that the higher density clumps have higher kinetic temperature and that the lower density clumps have lower kinetic temperature to better accuracy than in previous work. The kinetic temperature and density increase generally from a Type I GMC to a Type III GMC. We interpret that this difference reflects an evolutionary trend of star formation in molecular clumps. The R {sup 13}{sub 3-2/1-0} and kinetic temperature of the clumps are well correlated with the H{alpha} flux, suggesting that the heating of molecular gas with density n(H{sub 2}) = 10{sup 3}-10{sup 4} cm{sup -3} can be explained by stellar far-ultravoilet photons.« less